Autologous transfusion, that is blood taken from an individual and given back to that same individual at a later time, is a common practice in several surgical specialties. Examples include cardiovascular and orthopedic surgery. In an emergency setting, this process has also been used in the neonatal or newborn population. The interest in finding options to the use of homologous bank blood for the transfusion of premature infants has increased in recent years. An estimated 38,000 premature neonates at or below 1500 grams birth weight are born annually in the United States. Eighty percent of these neonates will require multiple red cell transfusions.
One researcher has calculated that multitransfused infants are typically exposed to eight different donors. Sacher, Transfus Med Rev 1989;3;39-54. Another researcher has conducted two different studies each of which has determined that 9.5% and 6.2%, respectively, of infants who receive a transfusion actually receive infected blood. Strauss, Transfusion 1989;26:419-22. Concern over the exposure of this population of sick neonates to infectious agents such as HIV; CMV; and Hep A, B and C, have led to the interest in developing options to the use of homologous bank blood in sick premature infants. These options include using a single donor from a blood bank or a directed family member, using an extended storage media and/or a multi-bag storage system, using recombinant erythropoietin to stimulate the neonates own marrow to manufacture red cells, and using autologous placental blood harvested at the time of delivery.
The use of placental blood is promising because the placenta can provide an adequate volume of blood for at least one 10 ml/kg transfusion in 87% of the cases. Sanford Anderson et al., Retrieval of Placental Blood From the Umbilical Vein to Determine Volume, Sterility, and Presence of Clot Formation, 146 AJDC 36-39 (January 1992). In addition to the possible use of placental blood for autologous transfusions, researchers are also exploring potential uses of specific elements of placental blood, e.g., removal of the white blood cells for storage and possible administration to the patient or a relative in the future as an alternative to a bone marrow transplant.
The use of placental blood has had the following limitations: safety of removal; sterility of the blood upon removal and storage; anticoagulation of the blood with the appropriate agent in time to prevent clotting of the specimens; minimizing trauma to the placenta and cord to limit the tissue damage and release of cell contents which might contaminate the placental blood; and efficiency of removal of the blood from the umbilical vessel. In fact, placental blood that is used for transfusion has a bacterial contamination rate of 12%. Sanford Anderson et al., Retrieval of Placental Blood From the Umbilical Vein to Determine Volume, Sterility, and Presence of Clot Formation, 146 AJDC 36-39 (January 1992). This bacterial contamination is usually a result of organisms that are on the surface of the umbilical vein.
As described below, elements of the present invention are unique and different from the existing prior art devices in light of the recognition of limitations as enumerated above.
The elimination of bacterial contamination of the placental blood, the need to minimize tissue damage by external forces such as pressure, and the need to properly anticoagulate the placental blood are critical if placental blood is to be used at a later date. The longer a placenta is exposed to the birth canal after the delivery of the infant, and the more manipulation it undergoes during the delivery process or later in a mechanical device, the greater the risk for the above complications to occur. The present invention is an improvement over the Knippscheer et al. device (U.S. Pat. No. 5,053,025) because it is designated to allow withdrawal of the placental blood from the umbilical vessel immediately after the delivery of the infant and before the delivery or manipulation of the placenta while it still resides within the uterus. In addition, the present invention uses the umbilical cord holder to position the umbilical vessel allowing the proper cleansing of its surface and the sterile withdrawal of the placental blood. Unlike the present invention, Knippscheer et al. allows the placental blood to "drain" from the contamination end of the cut placental cord.
The present invention also includes a valve system which allows the operator to serially remove placental blood and mix it with the appropriate volume and type of anticoagulant and transfer that mixture to an appropriate storage bag all within a closed sterile system and with minimal mechanical motion by the operator. This is an improvement over the Bonn device (U.S. Pat. No. 5,097,842) which does not allow for the variability in volume of blood obtained from infant to infant. Applicant has discovered in his research that it is critical to be able to mix the proper amount of anticoagulant with the volume of placental blood that is present. The manipulation of the withdrawal system must be minimal or the operator will inadvertently withdraw the needle from the umbilical vessel allowing loss or contamination of the placental blood. The combination of an umbilical cord holder and the valve system in the present invention addresses these issues.
The present invention is an improvement over Stone's device U.S. Pat. No. 5,059,168) because of its use of the umbilical cord holder, and the fact that the syringe must be in line with the axis of the umbilical vessel to allow one operator to carry out the operation of the placental blood withdrawal.
Hamilton (U.S. Pat. No. 3,344,785) and Clarke (U.S. Pat. No. 4,447,235) both disclose the use of a simple three way stopcock system which is not sufficient to allow the withdrawal of the placental blood, the admixture of the appropriate anticoagulant, and the transfer of that mixture to a storage bag all within a closed sterile system.